Electric-switch mechanism



W. RICHMOND.

ELECTRiC SWITCH MECHANISM.

, APPLICATION FILED 001.24,:911. RENEWED OCT. 12. I916.

Patel'lted July 15, 1919.

UNITED STATES PATENT OFFICE.

WALTER RICHMOND, 0F MEMPHIS, TENNESSEE, ASSIGNOR TO JOHN ELLIOTT JENKINS, OF CHICAGO, ILLINOIS.

ELECTRIC-SWITCH MECHANISM.

Application filed October 24, 1911, Serial No. 656,430. Renewed October 12, 1916.

To all whom it may concern:

Be it known that I, WALTER RICHMOND, a citizen of the United States, residing at Memphis, in the county of Shelby and State of Tennessee, have invented new and useful Improvements in Electric- Switch Mechanism, of which the following is a specification. I

My invention relates to electric switch mechanism which is especially adapted for use in automatically controlled systems, such as those which are thermostatically regulated.

One purpose of-my invention is to provide an electromagnetically operated switch which will operate upon either alternating or direct currents, with means for magnetically blowing out the are at the switch contacts when operating upon direct current.

Other objects will be apparent from the following description in connection with the accompanying drawings, in which Figure 1 is a plan view of an electric switch and controller mechanism embodying my invention, the energizing solenoid magnet being shown in section; and Fig. 2 is a detail View showing the manner of connecting the magnet core to the switch blade.

I have illustrated my electric switch mechanism in connection with a system of electric heaters 1, 2, for purposes of illustration, although it is useful in other applications, as will be evident to engineers. The actuating magnet is of the solenoid type, having two energizing coils 4, 5, which are adapted to move the core 6, in alternate directions to bring the switch blade 8 into engagement with the spring switch contacts 9, 9,'or 10, 10. Instead of securing the stem 12 of the switch blade rigidly to the core, I form the stem into a yoke frame 14 which surrounds the core so that the core may have a free initial movement within the yoke in both directions, striking the latter a hammer blow to insure a sudden movement of the switch blade from one pair of spring contacts-to the other pair. I

It is important when operating upon high voltage direct current, such as lighting circuits, that the are which follows the switch blade should be extinguished. One of the important features of my invention resides in the provision for blowing out the are after the movement of the switch blade in either direction. The spring contacts 9, 9,

Specification of Letters Patent.

Patented July 15, 1919.

Serial No. 125,334.

are located adjacent the coil 5, and within the influence of the magnetic field of said coil, whereby when the blade 8 is moved from the contacts 9, 9', due to the pull of the coil 5 upon the core 6, the are which follows the blade will be blown out by the field of the coil 5. In order to extinguish the arcwhich follows the blade when it is moving away from the contacts 10, 10, I provide a blow-out magnet 16, which is connected in shunt to the coil 4, and is located so that its magnetic field will be strongest opposite the upper portion of the contacts 9, 10, between which the arc is strongest.

The core 6 is somewhat longer than either of the energizing coils so as to extend into both coils in any position to insure the starting movement. I also provide an exterior magnetic sheath 18, for the purpose of concentrating and strengthening the magnetic field and thereby increasing the pull upon the core.

I have illustrated my electric switch mechanism in connection with a thermostatic controlling switch having a switch arm 20 carrying a contact 22, adapted to engage contacts 23 and 24 alternately. The arm is normally restricted by the spring 28, the tension of which can be changed by swinging the arm 29 into dotted line position. The switch arm 20 is moved against the spring tension by means of a fluid expansion thermostat having a thermal tube 30 and an expansion box 31, one face of which serves as a diaphragm and carries the anvil 32 which bears against the switch arm.

The current is brought in from the supply leads through the connection socket 35. With the parts in the position shown, the current enters at the socket' contact 35, and passes by way of the relay spring contact 10', through switch blade 8, spring con tact l0, and conductor 88 to the heater coils 1, 2, or other translating devices, and returns to the other socket contact 35 by way of the conductor 39. 1 When the circuit connections of the relay or electromagnetic switch mechanism are changed by the movement of the thermostatic switch arm 20, causing the contact 22 to engage the contact 24, a circuit will be established through the coil 4. Thereupon the core 6 will be drawn over into the coil 4, causing the blade 8 to move from the contacts 10, 10, into engagement with the contacts 9, 9, thereby breaking the circuitof the translating devices 1, 2. As the blade leaves the contact 10, the arc which follows will tend to maintain the circuit across the gap between the contacts 9, 10, and by Way of the blade 8, contact 9 to the connection with the socket contact 35*. This arc, however, will be extinguished by themagnetic field ofthe blowout magnet 16, the pole 16 of which is adjacent'to the gap. When the arc is extinguished the circuit will be broken through the coil 4:, blow-out magnet 16 in shunt thereto, and the heaters-1, 2, and current will not flow through any part of the apparatus' until the thermostatic switch arm 20 again establishes the circuit through the coil 5, by way of the contacts 22 and 23. In order that a circuit may be established through one relay coil or the other in all positions of the blade 8, I make the latter of a greater width than the gap between Qthe opposite pairs of spring contacts, as

indicated by the intermediate position of the blade shown in dotted lines.

It is known that a magnet which is properly proportioned according to present engineering standards to operate upon a direct current, will not operate upon an alternating current of the same voltage by reason of the reactance or counter electromotive force of the coil. The magnetic flux in a direct current magnet depends upon the number of ampere-turns, but in alternating current magnets it depends upon the voltage turns. Various expedients and auxiliary devices have been attached to or used in connection with electromagnets for the purpose of adapting them to use on both alternating and direct currents, but in so far as I am aware, no one has heretofore arranged the essential structural elements of the magnet adapted for useupon alternating currents, a-

laminated core is required. I then determine in the usual manner the number'of turns necessary to produce the required number of magnetic lines per square inch in the core when connected to an alternating current of the required voltage, say 50,000 lines per square inch, and this will cause the required magnetic pull. Now if the magnet were wound in the usual manner with the number of turns determined for the alternating current voltage, its resistance would rect current excitation it is the resistance alone which determines the current amperage and this must be proportioned to the voltage. In so far as I am aware, no one has discovered a manner of constructing a magnet so that it will 'be adapted to operate upon the same voltage for both alternating and direct currents and which I will now describe. of turns for'the alternating current of the required voltage as above described, I proportion the resistance of said number of turns so that the winding will permit the proper amperage upon connection to a di rect. current source of the same voltage. Having now the number of turns, deter mined for the alternating current and the resistance determined for the direct current, the length of wire for the desired size or cross-section becomes known and therefore the diameter of the coil. In this mannerl Having determined the number am enabled to provide an electro-magnet 'quired for the direct current and at the same time keep the number of turns to apoint which would not give too great a reactance of the coil when energized by the alternating current of the same voltage.

The advantages to be derived by the use of my invention will now be apparent. The

apparatus can be used with equal facility upon either direct or alternating current circuits of the same voltage, the alternating current being of any ordinary number of cycles up to say 133, which is above the ordinary commercial range. When operating upon direct current, the arc at the contacts will be blown out when the switch blade isoperating in either direction. In all positions of thevswitch blade, a circuit can be established through one or the other, ener-- gizing coil of the relay so that the core will be carried to the full extent of the stroke.

the spring contacts and to impart a sudden movement to the blade.

I have described the apparatus illustrated in the accompanying drawings in detail in order to fully disclose an embodiment of my invention, but I am aware that changes may be made therein Without departing from the spirit of my invention.

I claim I 1. An electro-magnetic apparatus adapted to operate upon either alternating or direct current circuits of the same voltage, comprising an energizin coil and a magnetizable core, the energizing Winding of said coil having the requisite ohmic resistance to operate upon a direct current of a certain voltage, and the Winding being so correlated to the magnetic body of the core that the reactance of the coil to alternating currents of commercial frequencies and the same voltage will cause the coil to operate upon the core with substantially the same effort as upon direct currents.

Copies of this patent may be obtained for five cents each, by addressing the 2. An electro-magnet adapted to exert substantially the same pull When operating upon either alternating or direct currents of the same voltage, comprising a magnetizable member and an energizing coil annularly spaced from said member to a distance such that the increased resistance caused by the increased length of Wire per turn due to the interposed annular space, and the correspondingly decreased number of turns for the length of Wire in the coil cause the mag netic field thereof to exert substantially the same eifort When energized with either direct or alternating currents of the same volt age.

In testimony whereof I have hereunto set my hand in presence of two subscribing Witnesses.

WALTER RICHMOND.

Witnesses:

CHARLES N. MURRAY, EDWIN S. CLARKsON.

Commissioner of Patents,

Washington, D. C. 

